By dropping a ball and seeing how long it takes to hit the ground or throw a ball up and time it as well
Answer:
D
Explanation:
Maybe your question is meant to be: which is not a wedge, because wedge is a combination of two inclined planes, use to separate bodies which are held together by large forces. Option A,B & C are all wedge except D.
As we know that spring force is given as

here we know that
F = 4 N
x = 2 cm = 0.02 m
now from the above equation we will have


so the elastic constant of the spring will be 200 N/m